E. Golubev, on behalf of the Millimetron team

ASC LPI

Millimetron Workshop 2019: Capabilities and Science Objective of Millimetron Space Observatory, 9-11 September 2019, Observatoire de Paris / LERMA, Paris

Thermal design of the Millimetron payload module

117.09.2019

Sunshields

Overall dimensions

20 m

11.2 m

2-sided aluminum-plated Kapton films

1st Sunshield

(MLI blanket)

Cryoshield

(actively cooled down to 20K)

2nd Sunshield

3rd Sunshield

4th Sunshield

Sun

-5°/ +85°

+X

+Y

+Z

217.09.2019

Sunshield structure

А - ААА

1st Sunshield (external)

2nd,3rd, 4th Sunshields

Sunshields consist of:

1. tubes from CFRP

2. flexible cord from aramid fiber

3. Two-sided aluminum-plated

polyimide film

4. MLI (R=50 𝒎𝟐∙𝑲

𝑾) 4

1

1

3

2

1

317.09.2019

Cryoshield structure

Structural ring with

synchronous deployment mechanics

Sandwich panel

(pure aluminum coating)

Two-sided aluminum-plated film

Flexible cord from aramid fiber

417.09.2019

Objectives of tests:

• film management

• film packaging

• deployment

• gravity offload system

Mock-up of cryoshield (full-scale)

1

Development status

Mock-up of the 1st sunshield (full-scale)

2

Engineering model of the deployment system

3

517.09.2019

Effective Radiation cooling

4,5K

39 mW 1.37 W 12.71 W 187.94 W 237.3 kW

heat radiated in to the Space

radiated heat flux

Cryo-container

Warm container

Level 4.5K

Level 300K

Level 100K

Level 20K

617.09.2019

“Matreshka” design

Cryo instrument container

«Warm» container

Actively cooled shield

~300 K

100 K

Radiator

Thermal shields(MLI blankets)

Actively cooled shield20 K

dramatically reduced thermal conductanceafter on-orbit deployment

Isogrid lattice structure

Decouple interface

low thermal conductivity

lightweight

100 K thermal interface

20 K thermal interface

Throw-over locks with prestressed cord

20 K

100 K

to Space

Thermalpanels

300 K

Cryo instrument container

Antenna4.5 K

Equivalent scheme of structure in terms of conductance

20 K

R1 R2

R3

R4

R5

R6

717.09.2019

Preliminary heat flow map (calculated)

817.09.2019

Budget of the heat loads on the temperature levels

* 100% margin estimated

Level

Radiation

Exchange,

W

Structure

Conduction,

W

Cable

network

Conduction*,

W

Heat

Dissipation of

instruments,

W

ΣQ, W

1-2K - - - 0.01 0.01

4K 0.030 0.002 0.018 0.10 0.15

20K 0.489 0.211 0.200 0.50 1.40

100K 1.480 2.940 1.580 10.00 16.00

917.09.2019

What could be implemented up to date?

Pulse Tube Cooler PT15K(Air Liquide)

2ST - Double stage Stirlingcooler (Sumitomo H.I.)

4K-class Joule Thomsoncooler (Sumitomo H.I.)

1K-class Joule Thomson cooler (Sumitomo H.I.)

TRL TRL5/6 (planned in 2019) TRL8 TRL8 TRL5 (life time test is ongoing)

Cooling power

800mW at 20K5W at 100K

>200mW at 20K>1W at 100K (EOL)

40mW at 4.5K (EOL) 10mW at 1.7K (EOL)19mW at 1.77K (withPT15K precooling)

Input power

300 W 80 W at EOL 90 W at EOL 75 W at EOL

Mass 21 kg 9.5 kg 15 kg 28 kg

Life time

? 3 years (5yrs as a goal) > 3 yrs (5yrs as a goal) >5 yrs

Compressor

Cold HeadCold Head →

Compressors (х4)

Cold Head →

Compressors (х2)

Cold Head

Compressor

1017.09.2019

How it could be realized? Active cooling system

1117.09.2019

Summary of active cooling system

Cryocooler type1-2 К

(J-Т)

4 К

(J-Т)

15 К

(2РТ)

20 К

(2РТ)

100 К

(2РТ )Total

Cooling power, W 0,02 0,04 - 0,80 5,00 -

Input power*, W 75 90 300 300 - 2535

Mass, kg 28,0 15,0 35,0 35,0 - 446

Required amount of coolers 1 4 1 6 - 12

Redundant cooler 1 1 1 1 - 4

Total amount 2 5 2 7 - 16

1217.09.2019

Thermal mockup (Scale 1:10)

The Cryo Test in the chamber

Primary Mirror

Sunshields

Development status

1317.09.2019

Conclusions

• The thermal design of the overall payload module and preliminary heat

load budget has been developed

• Implementation of 15K PT coolers (Air liquide) and 1K-, 4K-class Joule

Thomson coolers (Sumitomo H.I.) is one of the promising way to build the

active cooling system

• First validation test with the scale model demonstrated the very critical

parts of the thermal design

• Many aspects of the thermal design still need to be studied

1417.09.2019

Thank you for attention!